1. Technical Field
The invention relates to semiconductors and the fabrication thereof. In particular, the invention relates to contact and/or imprint lithography used to define one or both of micro-scale and nano-scale structures during semiconductor fabrication.
2. Description of Related Art
Photographic contact lithography and imprint lithography are examples of two lithography methodologies for defining micro-scale and nano-scale structures that generally involve direct contact between a patterning tool (e.g., mask, mold, template, etc.) and a substrate on which the structures are to be fabricated. In particular, during photographic contact lithography, the patterning tool (i.e., mask) is aligned with and then brought in contact with the substrate or a pattern receiving layer of the substrate. The pattern is then transferred to the pattern receiving layer using a photographic technique such as illuminating the patterning tool and pattern receiving layer with a radiation source (e.g., ultraviolet light, an electron beam, X-ray radiation, etc.) Similarly, in imprint lithography, the patterning tool (i.e., mold) is aligned with the substrate after which the pattern is printed on or impressed into a receiving surface of the substrate through a direct contact between the mold and receiving surface.
In both of contact lithography and imprint lithography, alignment between the patterning tool and the substrate general involves holding the patterning tool a small distance above the substrate while lateral and rotational adjustments (e.g., x-y translation and/or angular rotation) are made to a relative position of the tool and/or substrate. Ultimate alignment accuracy as well as an achievable patterning resolution may be affected by a degree to which the patterning tool and substrate are both mutually parallel and proximal during the alignment process. In addition, alignment accuracy may be affected by a drift or slip in the relative positioning of the aligned patterning tool and substrate that may occur as the tool is brought into contact with the substrate following alignment. Furthermore, a relative contact pressure between and an overall extent of the contact between the patterning tool and receiving surface of the substrate may affect an achievable patterning resolution and accuracy.